In order to analyze a sample for the presence of microorganisms (such as bacteria) it has hitherto been usual to either transfer a certain amount of the sample by a pipette to a dish, add a growth medium and either mix to distribute the bacteria or to simply distribute the bacteria on the surface of a solid growth substrate. After incubation examination is carried out to ascertain the extent of growth. In the cultivation of anaerobic microorganisms an anaerobic environment must be provided. The conventional manner of accomplishing this has been to place the dish, after distribution of the microorganisms in the growth medium (and after solidification of the growth medium, which generally comprises a nutrient broth and agar) in a closed growth vessel, where the oxygen of the air is removed (e.g. by hdyrogen gas and a catalyst which promotes the formation of water). This involves complicated and expensive techniques and equipment, and test errors can arise from mixing owing to contact with the air. Furthermore many of the microorganisms of interest are pathogenic, which means that risks for laboratory personnel may arise.